Texas Instruments TPD4S480 - A Protective Circuit for USB-C Connections
The USB-C connector has overtaken the world: few products use alternative interfaces. Sadly, the spread of the USB-C plug has also led to the arrival of devices that are not taking the specifications 100% seriously. With the TPD4S480, Texas Instruments provides a protective solution intended to ensure USB-C reliability in the presence of questionable devices.
USB-C and the USB PD (USB power delivery) specifications enable high power throughput by using high voltages: think up to 48 V to limit the impact of ohmic loads between the power source and the power sink. This high voltage, however, can also be present on the CC and SBU pins. While nominally rated for 5 V, a low-quality connector or an angled cable insertion can lead to pins shorting inside the connector.
One-Stop Shop for USB-C Protection
In principle, a USB-C port protection circuit can be constructed using various passive components such as Zener diodes. This kind of circuit tends to increase the weight and bill of materials of the printed circuit board housing the USB-C application.
A USB-C protection circuit based on the TPD4S480RUKR can use significantly less space. Its housing---the layout is shown in the figure below---is only 3×3 mm in size, much smaller than most Zener diodes.
From a schematic point of view, the TPD4S480 behaves the way one would expect it to.
Advanced Features for USB-PD Capabilities
A fully USB-PD-based device imposes various demands on port implementation: for example, the device must be able to accept power even if the internal battery is completely empty, and the transceiver thus has no power of its own.
In the case of the TPD4S480, Texas Instruments provides all the logic required for this specific use case---if dead-battery support is needed, a few connections on the PCB are all that is required to ensure reliable charging from a cold and dark state.
Another neat design capability is adapting classic PD controllers whose tolerances are not sufficient to satisfy the voltage levels required by the EPR specification. In this case, the part can drive an external field effect transistor, thereby enabling the grandfathering of the existing controller.
Finally, the TPD4S480 provides protection features, thereby ensuring that a device with a USB-PD power supply can handle various ESD specifications.
Conclusion
If a USB-PD-based device needs USB-C port protection, the TPD4S480 is an affordable and easy-to-integrate component. Its compliance with a wide variety of standards reduces the pressure on the actual USB controller---in short, a component recommended for every type of design.